What are two different fates of the products of catabolism? What is the role of these next steps in microbial growth?

Question

What will be an ideal response?

Answer 1

Two fates of catabolism products include:
1. Respiration: complete breakdown of organic molecules with electron transfer to a terminal electron acceptor such as O2. The benefit for the cell is that it can store energy as a proton potential, which can be used to generate ATP for the cell. Respiration yields far more energy from catabolism than does fermentation. For humans, respiration is synonymous with breathing; but in the absence of O2, many microbes use alternative electron acceptors, such as nitrate or sulfate. The use of a terminal electron acceptor other than O2 is called anaerobic respiration. Thus, microbes—unlike humans and other animals—have the capacity for anaerobic respiration.
2. Fermentation: partial breakdown of organic food without net electron transfer to an inorganic terminal electron acceptor. Microbes compensate for the low efficiency of fermentation by consuming large quantities of substrate and excreting large quantities of fermentation products. An advantage of fermentation is that the rapid accumulation of acids or ethanol can inhibit growth of competitors. Fermentation products are then excreted from the cell. The large quantities of substrate consumed in fermentation generate large amounts of waste products to be excreted.